Patent GB-701801-A (GB)
Title: Improvements in or relating to colour signalling attachments for electric hand lamps
IPC: F21Y101/00
Filed: 1951-01-15
Abstract: 701,801. Visible signalling apparatus. OLDHAM & SON, Ltd., and ROBERTS, A. O. Jan. 3, 1952 [Jan. 15, 1951], No. 1134/51. Class 118 (2). A signalling device for an electric hand lamp comprises a circular housing to be secured to the bulb chambers of a lamp and including a window at the front thereof and a back aperture to permit light from the bulb to pass through the housing to said window, transparent differently coloured screens each supported in said housing for pivotal movement about a pivot pin having its axis offset from the axis of the housing and for selective movement independently one of the other from an inactive position to an active position at which light passing through the housing is screened thereby, and manually operable screen actuating means extending into the housing to effect movement of the screens to and from their active and inactive positions. A housing 1 (Fig. 1), threaded to screw onto the bulb chamber 6 of an electric hand lamp 7, has a rear aperture 8, and a front window 10, preferably of light-diffusing glass. A reflector 118 is mounted inside the housing such that an aperture 37 therein is coaxial with the aperture 8 and spaced from it a small distance sufficient to permit the interposition of coloured screens between the two apertures. Two colour screens 18 and 19 (Fig. 3) are independently pivoted at 20 and normally held against stops 30, 31 by a spring 32 so as to be clear of the central aperture. The screen actuating means comprises a spindle 21 which extends into the housing 1 and is journaled partly in the back thereof and partly in the bulb chamber 6. A square portion 22 of the spindle 21 carries a lever 23 by which the spindle can be rotated to one of three positions located by spring-loaded balls 24 engaging holes in plates 26. The front end of spindle 21 is formed as an arcuate portion 27 which, when the lever 23 is moved to one side of its central or neutral position, engages a shoulder on the respective screen holder to move the screen into position over the aperture 8 as in Fig. 3. In an alternative embodiment of Figs. 5 and 6 a housing 1a is provided with internal threads at the rear to screw onto the bulb chamber of a portable electric hand lamp, and is externally threaded at the front to receive an apertured cover 40 which retains a glass or transparent plastic disc 10a and an apertured plate 61 in position as shown. Two screens 18a and 19a are separately pivoted at 20a and 20b respectively and are normally held clear of the central aperture in plate 61 by springs 32a and 32b. The actuating means comprises an annulus 41 having projections 44 which ride in a groove 45 in housing 1a and a projection 56 which carries a resilient member 58 holding a ball 59 in engagement between hemi-spherical protuberances formed in an arcuate plate 54 fixed to the inside of the back of the housing. A handle 49 facilitates rotation of the annulus 41 to one of three positions in the central one of which the screens 18a, 19a remain ineffective but on movement of the annulus to either side one of two' inward projections 27a, 27b engages its respective screen to move it to cover the aperture in plate 61. In a modification the aperture in the cover 40 is substantially of the same diameter as the interior of the housing 1a and the glass 10a is made light-diffusing or provided with prismatic facets moulded therein. In another modification the annulus 41 is dispensed with and the projections for operating the colour screens are carried by the cover 40 which is itself rotated to swing the colour screens into use, Fig. 8 (not shown), the locating member 56 being also secured to the cover.